The present invention relates generally to the area of rapid exchange (RE) catheters and more particularly to the area of over the wire--rapid exchange (OTW-RE) catheters having a unique combination of specific features not heretofore available in known prior art devices.
From the perspective of "over-the-wire" (OTW) users, "rapid exchange" (RE) catheters pose several problems related to the requirement that the wire lies outside of the catheter body. There are two distinct techniques for introducing a traditional rapid exchange catheter into a coronary stenosis, each of which poses it's own set of problems.
In the first such technique (hereinafter referred to as Method I), the guidewire is first advanced across the lesion ("bare wired"). Then, the RE catheter is advanced over the guidewire into the lesion.
Various problems occur using Method I, which leads many OTW users to dislike "bare wiring".
Initially, a balloon catheter surrounding the wire often provides needed support when wiring tortuous arteries. For example, when two or more curves are present, it is often helpful to advance the wire through the first curve and then bring the balloon catheter over the wire into the first curve before attempting to wire through the second curve. This becomes a matter of instinct and habit for the OTW user, however, this technique is not possible to use when "bare wiring".
Secondly, contrast injections cannot be made simultaneously with "bare wire" advancement due to leakage of contrast around the "O" ring of the "Y" connector. This problem can be solved by using a wire introducer which fits into the "O" ring, however the use of such a wire introducer adds an additional step to the procedure.
Further, the two pieces of equipment, wire and catheter, must be threaded through the guiding catheter separately when using the bare wire technique; first, the wire and second, the catheter. OTW users have become accustomed to threading the catheter and wire together in one movement through the guiding catheter. This procedure is more efficient and serves to avoid wasted time and motion for the OTW user.
In the second prior art technique (Method II), the guidewire is first loaded into a traditional rapid exchange catheter, then the combined system is advanced to the coronary ostium, the "O" ring is then tightened partially, and then the guidewire is advanced through the lesion. This allows the catheter to support the guidewire. In tortuous arteries the catheter can be moved partly into the artery to support the advancing guidewire.
There are also problems which arise using this second technique.
First, it is difficult to coordinate the advancement of the catheter and wire through the guide catheter together because the guidewire lies outside of the catheter. The guidewire can easily slip out of the guide catheter during advancement.
Secondly, the guidewire's advancement to the lesion is cumbersome because the guidewire exits the "O" ring alongside the catheter. For dye injections the "O" ring must be tight, therefore, simultaneous dye injections and wire advancement become awkward, if not impossible. Furthermore, the guidewire movement is always impinged by the "O" ring and its normal exit position, which is off to one side, feels awkward to the operator.
The aforementioned disadvantages of the currently available prior art devices can be overcome, in large part, by employing the OTW-RE catheter arrangement described in the present invention.
Various prior art references exist, of which the applicant is currently aware, which refer generally to the area of catheter systems and which are related to the device of the present invention. The most important amongst these are:
Bonzel, U.S. Pat. No. 4,762,129, which issued on Aug. 9, 1988, and concerns a dilation catheter having a tube, the operative end of which opens into an expandable balloon, and a segment of flexible tubing traversing the balloon, sealingly connected to the distal end of the balloon, and capable of being threaded by a guidewire;
Yock, U.S. Pat. No. 5,040,548, which issued on Aug. 20, 1991, and relates to an apparatus for introduction into the vessel of a patient comprising a guiding catheter adapted to be inserted into the vessel of the patient and a device adapted to be inserted into the guiding catheter; and
Kramer, U.S. Pat. No. 5,135,535, which issued on Aug. 4, 1992, teaches an intravascular catheter system, such as a dilatation catheter system for angioplasy procedures, which provides for the replacement of the catheter or the guidewire thereof during the procedure.
Scopton, et al, PCT Application No. WO 92/17236, relates to a catheter having a balloon at its distal most end, and having means for adjustably controlling the stiffness of the catheter shaft, and more particularly to a convertible-type balloon catheter having stiffener means disposed within the catheter. There is no teaching in this reference of any means for effecting the improvements taught by the inventor in the present application.
There are no other references of which the applicant is currently aware, which relate to the subject matter of the present invention.
None of the aforementioned prior art references teach an over the wire-rapid exchange catheter having the unique combination of specific features taught by the applicant in the present invention.
It is therefore an object of the present invention to provide an over the wire-rapid exchange catheter having a unique combination of characteristics not heretofore available in the prior art.
It is a further object of the present invention to provide an improved over the wire-rapid exchange catheter which serves to enhance the users ability to properly operate the guidewire/catheter and thus to allow the user to more expeditiously carry out the required catherization procedure.
It is another object of the present invention to provide a novel over the wire-rapid exchange catheter which allows the user the ability to rapidly separate the guidewire from the proximal guidewire channel of the catheter, as required during the procedure, in such a manner that the integrity of the OTW-RE catheter is preserved during the procedure, but which at the same time permits ease of removal of the guidewire from the proximal guidewire channel with a minimum of effort.
Lastly, it is an object of the present invention to provide an improved method for the operation of an over the wire-rapid exchange catheter using the improved device described herein.
These and other objects of the invention will be reflected in the course of the following discussion of the invention.